Draekai
I’m not sure if you’ll see this comment author but here’s a suggestion how about cutting off his legs ball busting him crippling his cultivation and cutting off his thumbs? That way he won’t be able to move or hold things and he’ll never be able to have sex or cultivate again he’ll essentially by a cripple with no future in cultivation or in society. Every day will be a living hell for him.
Actually, I think making him sit on a chair with bamboo growing into his ***hole is a good one. Also, there is a type of chemical that enhances pain receptors so inject him with that. Another recommendation is the classic needle method, the needles are barbed and tipped with the same poison mentioned before so it gets more painful each time. Then there is the heal and damage method where you carefully peel the skin off the person and heal him so he doesn't bleed, just really painful. We haven't even gotten into wolfs humping into the person and illusions.